<style>
.parent-node {
display: flex;
align-items: center
}
// 或者
.parent-node {
height: 300px;
position: relative;
}
.self-node {
width: 100px;
height: 100px;
position: absolute;
top: 50%;
transform: translate(0,-50%);
}
</style>
<body>
<div class="parent-node">
<div class="self-node" />
</div>
</body>
